[Evaluation of Mycobacterium fortuitum acyltrehaloses in the serologic diagnosis of pulmonary tuberculosis].

BACKGROUND

Several glycolipids of Mycobacterium tuberculosis are antigenic and their use in the serodiagnosis of pulmonary tuberculosis has been postulated. Acyltrehaloses (SL-IV) are among the strongest antigenic glycolipids of M. tuberculosis; similar compounds have been found in M. fortuitum. The aim of the present study was to evaluate the usefulness of the acyltrehaloses of M. fortuitum in the serodiagnosis of pulmonary tuberculosis.

METHODS

Two glycolipids, identified as triacyl- (TAT-MF) and diacyl- (DAT-MF) trehaloses, were studied by an ELISA method. Two independent analyses were carried out. In the first one, IgG and IgM were determined in sera from patients with pulmonary tuberculosis (84-24 bacteriologically not confirmed--), healthy individuals (46) and patients with respiratory pathologies other than pulmonary tuberculosis (38), using TAT-MF. In the second one, IgG was determined in sera from pulmonary tuberculosis patients (34) and from healthy individuals (20), using DAT-MF.

RESULTS

The sensitivity of the IgG ELISA using TAT-MF varied, according to the cut-off point, between 79.8 and 39.3%; the specificity values ranged between 83.3 and 98.8%. In sera from bacteriologically not confirmed pulmonary tuberculosis patients the sensitivity was 87.5-45.8%. The sensitivity for IgM was very low using TAM-MF (10.7-2.3%), with specificity values ranging from 77.4 to 100%. The sensitivity and specificity values of IgG using DAT-MF were, respectively, 34.3-9.3% and 90-100%.

CONCLUSIONS

The IgG ELISA using TAT-MF has similar values of sensitivity and specificity to those reported for the acyltrehaloses of M. tuberculosis, although this antigen, by itself, can not be used in the serodiagnosis of pulmonary tuberculosis. DAT-MF has no value in the serodiagnosis of pulmonary tuberculosis.